The present embodiments relate to a local coil for a magnetic resonance imaging system and a magnetic resonance imaging system, where the local coil or the magnetic resonance imaging system are embodied for the wireless transmission of operating energy or a reference signal.
Imaging systems based on a magnetic resonance imaging method (e.g., using nuclear spins, magnetic resonance tomography scanners) are proven in numerous applications. In this type of image acquisition, a strong static basic magnetic field B0 is used for the initial orientation and homogenization of magnetic dipoles that are to be examined. To determine material properties of an object under investigation to be depicted, the dephasing or relaxation time is determined after a deflection of the magnetization from the initial orientation so that different material relaxation mechanisms or relaxation times may be identified. The deflection may be effected by a number of HF pulses that are matched to the Larmor frequency of the dipoles to be excited. The Larmor frequency is determined by the properties of the material investigated and scaled with the strength of the basic magnetic field B0. For magnetic resonance measurements on biological examination objects, electromagnetic HF pulses with a Larmor frequency of 42.6 MHz and corresponding multiples may be used. This corresponds to the Larmor frequency of proton spins in a basic magnetic field B0 with a strength of 1 T (e.g., the multiplication factor corresponds to the strength of the basic magnetic field B0 in T).
Active implants such as, for example, pacemakers or brain stimulators are, therefore, designed such that the active implants have sufficient immunity to these typical Larmor frequencies for the examination of tissue. This immunity is demonstrated by the manufacturer of the implant so that electromagnetic signals with these frequencies may also be used in a magnetic resonance imaging system for test subjects with an active implant.
Other electromagnetic signals may also be used in a magnetic resonance imaging system. A known method to improve the magnetic resonance imaging is, for example, the use of local coils for magnetic resonance signal acquisition that are arranged in the immediate vicinity of the object under investigation during the magnetic resonance signal acquisition. This has advantages in the signal-to-noise ratio compared to magnetic resonance signal acquisition mechanisms at a greater distance from the object under investigation such as, for example, a body coil.
The cable connections to the local coils are difficult to handle since the test subject may need to be moved during the magnetic resonance imaging sequence in the tomography system, and thus, to provide optimum image acquisition, the cable routing is to be adapted to the local coil.